Hello All. I have had a set of Deco E3's for a couple of years. I added a set of 3 S3s last year and it all seems to work ok. I have never had much joy with the app outside actually setting the units

Hello All. I have a set of 3 E4 TP link deco mesh expanders. I need to add one more - my question is can i only buy an "add on" unit? or could I buy a net new set of 2 x E4's for example and use them